He said: “Concerns people had about the Post Office becoming independent from Royal Mail were always misplaced.

“Separation is part of our cure, but the ten year deal struck between Royal Mail and the Post Office will give sub-postmasters and others greater confidence.

“Coupled with winning new contracts such as those with UKBA and Westminster Borough and the successful pilots of new operating models, the signs are extremely encouraging for the future of the Post Office.”

Income from Royal Mail business services currently accounts for around a third of sub-postmasters’ income.

George Thomson, the general secretary of the National Federation of Sub-Postmasters, said the deal was “essential for the future wellbeing of our post offices”.

He said: “Sub-postmasters welcome the security this news brings, which will help provide them with the confidence necessary to invest in their businesses for the future.

“Without this deal, sub-postmasters would have faced even greater difficulties in running their businesses and continuing to provide vital services to their communities.”

Paula Vennells, Managing Director of Post office Ltd, added: "A long term relationship with Royal Mail ensures we continue to provide the unrivalled access and great customer service in mails and parcels services, which individuals and business customers want from the Post Office.

“This vital agreement, along with our ambitious plans for growth in government services, our branch investment and modernisation programme, and our development of digital services will all help to build a long term and sustainable Post Office.”

Baroness Sayeeda Warsi, the Tory party’s co-Chairman: “In Opposition the Conservative Party campaigned tirelessly to overturn Labour’s cuts to our Post Offices, which saw them close over 6,500 in a decade.

“Rather than protect services Labour destroyed local communities for whom the Post Office was a vital link. Now the future of the Post Office is secured.”